The Sydney Harbour Bridge celebrates its 75th anniversary today, March 19. Construction started on the granite pillars 1923 while work on the steel arch started in 1929. The arch spans 509m (1,559 feet) and weighs 39,000 tons. The top is 134m (415.4 feet) above sea level, although the height can increase by up to 180mm (7 in) on hot days as the steel expands.

Designed to carry road traffic, trains and trams, the bridge opened on March 19 1932. Sixteen men died while working on its construction. At a total cost of £10,057, 170.7s.9d, it cost twice as much as the original estimate – it took until 1988 to finish paying off the loans.

Now one of the most iconic bridges in the world, Sydney Harbour Bridge spans Sydney Harbour, joining north and south Sydney. This view looks east, towards the Pacific – the opera house and the city’s financial district are on the right.

The bridge has been open to tourists since 1998. Tours run all day, from dawn to dusk and are only cancelled for electrical storms or high wind. Climbs start on the eastern side of the bridge and ascend to the top. At the summit, the group crosses to the western side of the arch for the descent.